Iron deficiency anaemia is the most common form of anaemia in the UK, affecting around 2–3% of adult men and postmenopausal women, and up to 9–12% of premenopausal women. It occurs when the body lacks enough iron to produce sufficient haemoglobin — the protein in red blood cells that carries oxygen around the body. It is highly treatable but requires identifying and addressing the underlying cause.
Iron Deficiency Anaemia Symptoms
Symptoms of iron deficiency anaemia develop gradually as iron stores become depleted. Common symptoms include persistent tiredness and fatigue (the most common symptom), weakness, shortness of breath on exertion, pale skin and pale inner eyelids, heart palpitations, dizziness or lightheadedness, headaches, difficulty concentrating and brain fog, cold hands and feet, brittle or spoon-shaped nails (koilonychia), hair loss, a sore or inflamed tongue (glossitis), mouth sores, and a craving to eat non-food substances such as ice, clay, or chalk (pica). In severe anaemia, chest pain and fainting can occur.
Causes of Iron Deficiency Anaemia
Iron deficiency anaemia has three main causes: inadequate dietary iron intake, impaired iron absorption, or iron losses from the body. In the UK, the most common causes include heavy menstrual periods (the leading cause in premenopausal women), pregnancy and breastfeeding (increased iron demand), gastrointestinal blood loss from conditions such as peptic ulcers, gastritis, oesophagitis, bowel cancer, polyps, or haemorrhoids, coeliac disease (impairing iron absorption in the small intestine), inflammatory bowel disease (Crohn’s disease or ulcerative colitis), vegetarian and vegan diets (plant-based iron — non-haem iron — is less well absorbed than haem iron from meat), regular use of NSAIDs (aspirin, ibuprofen) which can cause GI bleeding, and after weight loss surgery (particularly gastric bypass).
In men and postmenopausal women, iron deficiency anaemia is particularly significant as it usually indicates gastrointestinal blood loss, which may be a sign of bowel cancer or another serious condition. All men and postmenopausal women with iron deficiency anaemia should be investigated for a gastrointestinal cause — NICE recommends an urgent colonoscopy or other investigation.
How Is Iron Deficiency Anaemia Diagnosed?
Iron deficiency anaemia is diagnosed with blood tests. A full blood count (FBC) typically shows a low haemoglobin level (below 130g/L in men, below 120g/L in women, below 110g/L in pregnancy) with small, pale red blood cells (microcytic hypochromic anaemia). Ferritin (the iron storage protein) is the most sensitive marker — a low ferritin (typically below 15–30 micrograms/L) confirms iron deficiency. Other tests including serum iron, transferrin, and transferrin saturation may be measured. Blood tests are available from your GP or privately.
NHS Treatment: Iron Supplements
Oral iron supplements are the first-line treatment for iron deficiency anaemia. The most commonly prescribed supplement in the UK is ferrous sulphate 200mg tablets (providing 65mg elemental iron per tablet), typically taken two to three times daily. Ferrous fumarate and ferrous gluconate are alternatives that may cause fewer gastrointestinal side effects for some people. Iron is best absorbed when taken on an empty stomach, but this increases the likelihood of nausea and stomach upset — taking with food reduces side effects but also reduces absorption. Taking iron with vitamin C (e.g. a glass of orange juice) significantly enhances absorption.
Common side effects of oral iron include nausea, constipation, dark or black stools (which are harmless), abdominal cramps, and diarrhoea. Taking iron every other day (rather than daily) has been shown in some studies to reduce side effects while maintaining effectiveness. Iron supplements should be continued for at least three months after haemoglobin normalises to replenish iron stores. Haemoglobin levels typically begin to rise within 2–4 weeks of starting treatment.
Intravenous (IV) iron infusion is an alternative for people who cannot tolerate oral iron, have malabsorption, require rapid repletion, or have conditions where oral iron is insufficient. IV iron infusions are available on the NHS (typically via hospital day units or GP-initiated outpatient referral) and in private clinics. They replenish iron stores rapidly — often in a single infusion — with results typically seen within two to four weeks.
Dietary Sources of Iron
Two forms of dietary iron exist. Haem iron is found in red meat (beef, lamb, pork), liver, and other organ meats, and is absorbed efficiently (15–35% absorption rate). Non-haem iron is found in plant foods — lentils, chickpeas, kidney beans, tofu, fortified cereals, dark green leafy vegetables (spinach, kale), dried fruit (apricots, raisins), nuts and seeds, and wholemeal bread. Non-haem iron is less efficiently absorbed (2–20%) but absorption is significantly enhanced by consuming vitamin C-rich foods at the same meal and reduced by tea, coffee, calcium, and phytates.
The NHS recommends that men aged 19–64 consume 8.7mg of iron per day and women aged 19–49 consume 14.8mg per day (higher due to menstrual losses). Women over 50 and all men need only 8.7mg per day.
Iron Deficiency Without Anaemia
It is possible to be iron deficient without yet being anaemic — iron stores become depleted before haemoglobin falls. This is called iron deficiency without anaemia and can still cause symptoms including fatigue, brain fog, reduced exercise tolerance, and hair loss. A low ferritin level on blood testing confirms this. Treatment with iron supplements or dietary changes is still appropriate and can significantly improve symptoms even without frank anaemia.
Important: Iron deficiency anaemia always requires identifying and treating the underlying cause, not just replacing iron. Unexplained iron deficiency — particularly in men and postmenopausal women — should prompt investigation for gastrointestinal blood loss. Please speak to your GP if you are concerned about anaemia.
Related Health Guides on YourHealthXpert
Explore these related NHS-aligned health guides:
- Anxiety and Depression — iron deficiency anaemia is a common and treatable cause of low energy and low mood
- Vitamin B12 Deficiency — B12 deficiency causes anaemia with similar symptoms to iron deficiency
- Vitamin D Deficiency — often coexists with iron deficiency, especially in groups with poor nutrition
- Menopause — heavy periods in perimenopause are a leading cause of iron deficiency in women over 40
- Coeliac Disease — untreated coeliac disease impairs iron absorption and is a common cause of iron deficiency